The rotors of electric machines are usually mounted with two roller bearings, so that each is mounted at the end of a shaft end. In most cases, one more gear is arranged between the E-machine and the joint gear. With an electric axle drive that has two E-machines, friction losses are thus always generated in all four bearings.
DE 42 36 124 A1 discloses an electric vehicle having a drive unit that is provided with two electric engines arranged on one axle, which are respectively connected by means of a planetary gear to a drive wheel. The drive shafts of both electric engines are connected to each other via a differential device. Both drive shafts are respectively mounted with two roller bearings.
DE 37 25 620 C2 describes a drive and brake apparatus with recovery of braking energy for motor vehicle, in particular for four-wheel drive motor vehicles, wherein each driven vehicle wheel is provided with an electric engine that also works as a generator. The driven vehicle wheels are preferably connected by means of a planetary gear to a support brake. Both electric engines are arranged on one axle in a joint housing, which is elastically mounted on the car body. The housing of the support brakes is mounted on a roller bearing of the engine housing.
From DE 10 2009 033 531 A1 is known a drive device for a motor vehicle, wherein a hollow portal axle accommodates two electric machines which are assigned to a respective wheel of the vehicle. Between the electric machine and the vehicle wheel associated with it is arranged a reduction gear which is linked via a joint shaft to the associated vehicle wheel. The bearing of the rotors of both electric machines is not described in more details.